The present invention is directed to insecticidal devices. More particularly, the present invention is directed to devices for the deployment of insecticides to kill mosquitoes and other biting insects.
Mosquitoes and other biting flies are prevalent throughout every region inhabited by humans. Besides presenting an ongoing nuisance, these pests serve as the vectors for transmission of blood-borne diseases between species of warm-blooded animals (i.e., birds and mammals). The disease organisms, such as the West Nile virus, which is spread by the common mosquito culex pipiens, are carried in the blood meals taken by the adult females of the biting insect species.
Adult biting flies may live on more than one food source, but the female requires one or more blood meals to produce eggs. The female insect surveys the ambient environment for suitable sources of blood, relying first on chemical signals in the atmosphere, then on more prey-specific signals such as movement, body heat, color contrast, and the presence of certain organic compounds. Once the blood meal has been digested, the female must deposit her eggs in water or in a damp environment subject to flooding, where the subsequent stages of development and growth take place.
A common technique of controlling mosquitoes and other biting insects is to deposit poisonous substances into the preferred breeding environments of the targeted insect species, typically as an insecticide spray or fog. There are a number of disadvantages to using sprays or fogs for insect control. For example, it is difficult to limit the exposure of non-targeted species to the poisonous substances that are deposited in the treated areas. Moreover, the insecticides may be transported some distance away from the treated areas as aerosols or in water. Excessively large amounts of the insecticides may be required to ensure adequate control of the insects within the treated areas. The insecticides themselves may be quite expensive, particularly if they are specifically toxic to the targeted biting insects.
A number of devices for killing adult insects attempt to attract the insects to the device, using one or more of a variety of lures selected according to the natural feeding or reproductive behavior of the targeted insects. Representative types of such devices are disclosed in the following U.S. patents:
U.S. Pat. No. 3,826,036 discloses a packet-like insect killing device that employs a substrate with a pheromone attractant and a chemical insecticide for attracting and killing insects. The substrate is held within a cage-like enclosure that facilitates handling the device while avoiding contact between non-targeted animals and the insecticide.
U.S. Pat. No. 3,931,692 discloses a layered device having insecticide-laden food particles within a perforated fibrous web for attracting and killing cockroaches. The disclosed device also includes wing-like features extending from a bottom web for handling and positioning the device while avoiding contact with the insecticide. U.S. Pat. Nos. 4,879,837, 5,046,280 and 5,775,026 each disclose small devices that utilize pheromones or other chemical attractants and a contact poison for killing the insects attracted to the target. The device disclosed in U.S. Pat. No. 5,046,280 includes a mesh covering over the substrate containing the attractant and poison to prevent non-targeted animals from coming in contact with the poison. As discussed in U.S. Pat. No. 5,775,026, the use of contact poisons becomes problematic in humid or wet environments, such as the flooded areas where mosquitoes and other biting flies breed.
U.S. Pat. Nos. 5,595,018, 5,657,576, 6,050,025 and 6,425,202, disclose devices that employ bait to attract mosquitoes to electric coils where the mosquitoes are then killed by electrocution. The bait in these devices generally simulates the physical characteristics of prey such as heat (U.S. Pat. No. 5,595,018) or, in the more sophisticated devices, odoriferous substances or warm, pulsing fluid (U.S. Pat. Nos. 5,657,576, 6,050,025 and 6,425,202). The disclosed devices use electricity, rather than poison, to kill the insects, and are poorly suited for use in remote areas or in areas that are wet or flooded.
Other U.S. patents disclose devices for dispensing insecticides into the water bodies where biting flies pass through their larval or nymphoid stages of development. For example, U.S. Pat. Nos. 4,631,857, 4,218,843 and 4,228,614 disclose insecticide delivery devices that are designed to float upon the surfaces of water bodies while dispensing poisons or microorganisms to kill larvae or nymphs in the ambient water environment.
The present invention is directed to insecticide packets for preferentially delivering poison to adult female biting insects in an inexpensive and environmentally safe manner.
A preferred embodiment of the insecticide packet comprises an envelope for enclosing an insecticide for ingestion by a biting insect. The envelope includes a permeable web that is penetrable by the mouthparts of a biting insect, such that volatile substances (e.g, insect attractants) within the envelope will migrate to the ambient environment. The envelope also includes a plurality of pins extending outwardly from the envelope to discourage non-targeted animals from attempting to ingest the envelope or its contents.
In another preferred embodiment, the envelope of the insecticide packet is protected by an outer pocket. The pocket is provided with a second permeable web that is in contact with permeable web of the envelope to facilitate the migration of volatile substances from the envelope to the ambient environment. A plurality of pins extends outwardly from the pocket.
In yet another preferred embodiment, the envelope of the insecticide packet is enclosed within a pocket that has holes to expose the permeable web of the envelope to the ambient environment.
Another preferred embodiment of the present invention includes an insecticide packet and a buoyant support arranged so that at least a portion of the permeable web of the envelope is above the water line when the packet and buoyant support float on the surface of a water body.
Preferably, the insecticide includes a stomach poison for the types of biting insect targeted by the insecticide package mixed with a food that is preferred by the biting insects. For example, a combination of boric acid and cattle blood may be effective to kill female biting insects, including mosquitoes. Volatile organic compounds, such as odoriferous compounds from the food itself, may also be included with the insecticide to attract the biting insects to the insecticide packet.